DataGridColumnCollection.Clear Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Removes all DataGridColumn-derived column objects from the DataGridColumnCollection collection.
public:
void Clear();public void Clear ();member this.Clear : unit -> unitPublic Sub Clear ()Examples
The following code example demonstrates how to use the Clear method to empty the DataGridColumnCollection collection before adding new columns to the collection.
<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<script language="C#" runat="server">
ICollection CreateDataSource()
{
DataTable dt = new DataTable();
DataRow dr;
dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
dt.Columns.Add(new DataColumn("StringValue", typeof(string)));
dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));
for (int i = 0; i < 9; i++)
{
dr = dt.NewRow();
dr[0] = i;
dr[1] = "Item " + i.ToString();
dr[2] = 1.23 * (i + 1);
dt.Rows.Add(dr);
}
DataView dv = new DataView(dt);
return dv;
}
void Page_Init(Object sender, EventArgs e)
{
// Empty DataGridColumnsCollection collection.
ItemsGrid.Columns.Clear();
// Create dynamic columns to add to Columns collection.
BoundColumn IntegerColumn = new BoundColumn();
BoundColumn StringColumn = new BoundColumn();
BoundColumn PriceColumn = new BoundColumn();
IntegerColumn.HeaderText="Item Number";
IntegerColumn.DataField="IntegerValue";
StringColumn.HeaderText="Item";
StringColumn.DataField="StringValue";
PriceColumn.HeaderText="Price";
PriceColumn.DataField="CurrencyValue";
// Add columns to Columns collection.
ItemsGrid.Columns.Add(IntegerColumn);
ItemsGrid.Columns.Add(StringColumn);
ItemsGrid.Columns.Add(PriceColumn);
}
void Page_Load(Object sender, EventArgs e)
{
if (!IsPostBack)
{
// Load this data only once.
ItemsGrid.DataSource= CreateDataSource();
ItemsGrid.DataBind();
}
}
</script>
<head runat="server">
<title>DataGridColumnCollection Clear Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataGridColumnCollection Clear Example</h3>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AutoGenerateColumns="false"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<Columns>
<asp:BoundColumn
HeaderText="Item Number"
DataField="IntegerValue"/>
<asp:BoundColumn
HeaderText="Item"
DataField="StringValue"/>
<asp:BoundColumn
HeaderText="Price"
DataField="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</form>
</body>
</html>
<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<script language="VB" runat="server">
Function CreateDataSource() As ICollection
Dim dt As New DataTable()
Dim dr As DataRow
dt.Columns.Add(New DataColumn("IntegerValue", GetType(Int32)))
dt.Columns.Add(New DataColumn("StringValue", GetType(String)))
dt.Columns.Add(New DataColumn("CurrencyValue", GetType(Double)))
Dim i As Integer
For i = 0 To 8
dr = dt.NewRow()
dr(0) = i
dr(1) = "Item " + i.ToString()
dr(2) = 1.23 *(i + 1)
dt.Rows.Add(dr)
Next i
Dim dv As New DataView(dt)
Return dv
End Function 'CreateDataSource
Sub Page_Init(sender As Object, e As EventArgs)
' Empty DataGridColumnsCollection collection.
ItemsGrid.Columns.Clear()
' Create dynamic columns to add to Columns collection.
Dim IntegerColumn As New BoundColumn()
Dim StringColumn As New BoundColumn()
Dim PriceColumn As New BoundColumn()
IntegerColumn.HeaderText = "Item Number"
IntegerColumn.DataField = "IntegerValue"
StringColumn.HeaderText = "Item"
StringColumn.DataField = "StringValue"
PriceColumn.HeaderText = "Price"
PriceColumn.DataField = "CurrencyValue"
' Add columns to Columns collection.
ItemsGrid.Columns.Add(IntegerColumn)
ItemsGrid.Columns.Add(StringColumn)
ItemsGrid.Columns.Add(PriceColumn)
End Sub 'Page_Init
Sub Page_Load(sender As Object, e As EventArgs)
If Not IsPostBack Then
' Load this data only once
ItemsGrid.DataSource = CreateDataSource()
ItemsGrid.DataBind()
End If
End Sub 'Page_Load
</script>
<head runat="server">
<title>DataGridColumnCollection Clear Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>DataGridColumnCollection Clear Example</h3>
<b>Product List</b>
<asp:DataGrid id="ItemsGrid"
BorderColor="black"
BorderWidth="1"
CellPadding="3"
AutoGenerateColumns="false"
runat="server">
<HeaderStyle BackColor="#00aaaa">
</HeaderStyle>
<Columns>
<asp:BoundColumn
HeaderText="Item Number"
DataField="IntegerValue"/>
<asp:BoundColumn
HeaderText="Item"
DataField="StringValue"/>
<asp:BoundColumn
HeaderText="Price"
DataField="CurrencyValue"
DataFormatString="{0:c}">
<ItemStyle HorizontalAlign="right">
</ItemStyle>
</asp:BoundColumn>
</Columns>
</asp:DataGrid>
</form>
</body>
</html>
Remarks
Use this method to remove all DataGridColumn-derived column objects from the DataGridColumnCollection collection.
Note
The Count property is automatically set to 0 after this method is used.
Applies to
See also
Współpracuj z nami w serwisie GitHub
Źródło tej zawartości można znaleźć w witrynie GitHub, gdzie można również tworzyć i przeglądać problemy i żądania ściągnięcia. Więcej informacji znajdziesz w naszym przewodniku dla współtwórców.
